JPH0616463A - Calciumsilicate molded body and its manufacture - Google Patents

Abstract

PURPOSE:To remarkably improve adiabatic performance of a calciumsilicate molded body. CONSTITUTION:This calciumsilicate molded body is formed by incorporating an inorganic inactive substance of at least one kind among carbon black, Fe3O4, ZrO2, TiO2, Fe2O3 and B4C physically integrated to or wrapped with the secondary particles of a calciumsilicate crystal, and the content of the inactive substance is 10wt.% to 21wt.% in the molded body. While a raw material slurry incorporating a silicate raw material, a lime raw material and water is heated and stirred under pressure, a hydrothermal reaction proceeds to prepare an aqueous slurry of the calciumsilicate crystal secondary particles and is subsequently molded and dried and to produce the objective calciumsilicate molded body. At this time, the inorganic inactive substance which is at least one kind of the carbon black, Fe3O4, ZrO2, TiO2, Fe2O3 and B4O is incorporated into the raw material slurry in the quantity of 10wt.% to 21wt.% based on the molded body.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a calcium silicate compact having remarkably improved heat insulation performance and a method for producing the same.

[0002]

BACKGROUND ART Calcium silicate compacts are lightweight, have excellent heat insulating properties, have great fire resistance, and have many other properties, so they are used in various fields.
Widely used.

In recent years, in the fields of heat insulating materials, heat insulating materials and the like, there has been a demand for calcium silicate compacts having even higher heat insulating performance.

[0004]

DISCLOSURE OF THE INVENTION The present invention meets the above-mentioned needs, and an object thereof is to provide a calcium silicate compact having a significantly improved heat insulating performance and a method for producing the same.

The present invention prepares an aqueous slurry of calcium silicate crystal secondary particles by subjecting a raw material slurry containing a silicic acid raw material, a lime raw material and water to a hydrothermal synthesis reaction while heating and stirring under pressure, and then molding the slurry. In the method for producing a calcium silicate compact by drying, carbon black,
Fe ₃ O ₄ , ZrO ₂ , TiO ₂ , Fe ₂ O ₃ and B ₄
The present invention relates to a method for producing a calcium silicate compact, which comprises adding an inorganic inactive substance, which is at least one of C, to the raw material slurry in an amount of 10% by weight or more and less than 21% by weight in the compact.

The calcium silicate compact of the present invention obtained by the above method comprises secondary particles of calcium silicate crystals, and carbon black which is physically integrated with the secondary particles in a state of being surrounded by the secondary particles. Fe ₃ O ₄ , Zr
At least one of O ₂ , TiO ₂ , Fe ₂ O ₃ and B ₄ C
It is characterized by containing an inorganic inactive substance as a seed, and the content of the inactive substance is 10% by weight or more and less than 21% by weight in the molded body.

The molded product obtained according to the present invention has a remarkably improved heat insulating performance due to the inert substance and has sufficient practical strength.

The production method of the present invention is basically the silicic acid described in JP-B-45-25771, except that a specific inorganic inactive substance is added to the raw material slurry before the hydrothermal synthesis reaction under stirring. A raw material slurry containing a raw material, a lime raw material and water is hydrothermally synthesized under heating and stirring under pressure to prepare an aqueous slurry of calcium silicate crystal secondary particles, which is then molded and dried to form a calcium silicate compact. It is similar to the manufacturing method.

As the silicic acid raw material used in the present invention, any of those conventionally used for the production of calcium silicate compacts can be effectively used, and as the crystalline silicic acid raw material, silica stone, silica sand and the like can be used. Silica gel as a raw material for crystalline silicic acid,
Examples thereof include silica flour (ferrosilicon dust, etc.), white carbon, diatomaceous earth, silica obtained by reacting hydrous silicofluoric acid by-produced in the wet phosphoric acid production process, and aluminum hydroxide. Further, as the lime raw material, any of those conventionally used can be used, and quick lime, slaked lime, carbide slag and the like can be exemplified.

Further, CaO / Si which is a raw material of silicic acid and a raw material of lime
The O ₂ molar ratio is about 0.70 to 0.90 when trying to synthesize a tobermorite crystal, and about 0.90 to 1.15 when trying to synthesize a xonotlite crystal.

In the present invention, a raw material slurry is prepared by further adding an inert substance and water to the silicic acid raw material and the lime raw material.

The inorganic inactive substance in the present invention includes
Carbon black, Fe ₃ O ₄ , ZrO ₂ , TiO ₂ ,
At least one of Fe ₂ O ₃ and B ₄ C is used. The particle size of the inert substance used is usually 0.001 to 12
About 0 μm, preferably 0.001 to 100 μm is suitable.

In the present invention, the inert substance is preferably added so that the content in the molded product is 10% by weight or more and less than 21% by weight. At this time, if the addition amount does not reach 10% by weight, the improvement of the heat insulating property tends to be insufficient.

In the present invention, it is necessary to incorporate an inactive substance into the raw material slurry before the hydrothermal synthesis reaction to carry out the hydrothermal synthesis reaction to produce secondary particles of calcium silicate crystals. It is possible to significantly improve the heat insulating property while maintaining sufficient practical strength.

Conventionally known additives may be added to the raw material slurry, and inorganic fibers such as asbestos and rock wool may be used as the additives at this time.

When preparing the raw material slurry, the amount of water is 5 times by weight or more, preferably 10 times the solid content of the raw material slurry.
˜50 times by weight, and in the case of producing a lightweight body having a density of about 0.1 g / cm ^3, it is 15 to 50 times by weight, preferably 20 to
It is appropriate that the weight is 40 times.

The raw material slurry thus prepared is then subjected to a hydrothermal synthesis reaction with stirring. This reaction is usually 4
Kg / cm ² or more, preferably at the saturated vapor pressure of 6~30Kg / cm ^2. By this reaction, a secondary particle having an outer diameter of about 5 to 150 μm, which is mainly composed of a tobermorite crystal or / and a xonotlite crystal and is three-dimensionally entangled, is generated and coexists in the raw material slurry. The inactive substance present is physically integrated with the secondary particles in a state of being wrapped in the secondary particles, and a slurry in which these are uniformly dispersed in water is obtained.

In the present invention, if necessary, various additives may be further added and mixed prior to molding. As the additive in this case, those which have been used for the production of calcium silicate compacts can be used in a wide range, and fibers, clays, cements, various binders and the like can be exemplified.

In the present invention, an aqueous slurry comprising secondary particles of calcium silicate crystals, an inert substance and, if necessary, other additives is molded by a conventional method such as press dehydration molding, centrifugal dehydration molding, etc. and dried. A calcium silicate compact can be obtained. During molding, if necessary, an aqueous slurry containing the above-mentioned inactive substance is placed in a mold for press dehydration molding, and an inactive substance-free calcium silicate crystal obtained by a conventional method is further formed thereon. The slurry may be put into a mold and subjected to press dehydration molding, or the reverse operation may be performed to obtain a laminated molded body.

The calcium silicate compacts obtained by the present invention can be easily manufactured from high density to low density lightweight bodies, but especially low density lightweight bodies such as bulk density of 0.
Settling volume of 5 when producing molded bodies of about 1 g / cm ³
It is preferable to use more than ml of lime milk. Particularly preferred is a sedimentation volume of 10 ml or more.

The settling volume of lime milk means 50 ml of lime milk having a water-to-lime solid content ratio of 120 times and an inner diameter of 1.3 cm.
The volume of sedimentation of lime particles after being left for 20 minutes in a graduated cylinder having a volume of 50 cm ³ is shown in ml.
A large settling volume means that lime is well dispersed in water, is in a stable state, and has high reactivity. By using lime milk having a large sedimentation volume, the apparent density of the secondary particles of the obtained calcium silicate crystals becomes low, which facilitates the production of a low-density lightweight body.

[0022]

EXAMPLES The present invention will be specifically described with reference to the following examples. However, parts and% in the following examples represent parts by weight and% by weight, respectively, and various physical properties are measured by the following methods.

(A) Bending strength: Measured according to the method of JIS A 9510.

(B) Thermal conductivity: Measured according to the cylindrical method of JIS A 9510.

Example 1 Quicklime (95% of CaO) was dissolved in warm water at 80 ° C.,
The sediment volume of lime milk obtained by dispersing in water with a homomixer was 18 to 21 ml. Silica powder (SiO ₂ 94%) with an average particle size of 7.1 μm was added to the above lime milk with CaO / S.
In addition to iO ₂ molar ratio is 1.00, further predetermined amount of Fe ₂ O ₃ powder (hematite, average particle diameter 0.51
μm) and water were added and mixed so that the total amount of water would be 20 times the weight of the solid content to obtain a raw material slurry. This was stirred at a saturated steam pressure of 12 kg / cm ² and a temperature of 191 ° C. in an autoclave while rotating a stirring blade at a rotation speed of 40 rpm, and hydrothermal synthesis reaction was carried out for 5 hours to obtain a slurry of calcium silicate crystals.

The crystal slurry obtained above was heated at 100 ° C. for 24 hours.
When dried for an hour and analyzed by X-ray diffraction, a peak of hematite crystals was observed in the case where the xonotlite crystal and the Fe ₂ O ₃ powder were added.

Observation of these crystal slurries with an optical microscope and a scanning electron microscope revealed that, in all the slurries, zonotolite crystals were three-dimensionally entangled to form a spherical shell having an outer diameter of 5 to 150 μm. Secondary particles were observed. In addition, it was confirmed that, in the case of adding the Fe ₂ O ₃ powder, the hematite crystal was wrapped in the secondary particles of the xonotlite crystal and physically integrated.

Next, 90 parts (solid content) of the crystal slurry obtained above was mixed with 7 parts of glass fiber and 3 parts of Portland cement.
Parts were added, and the mixture was subjected to press dehydration molding and dried at 100 ° C. for 24 hours to obtain a cylindrical molded body having an inner diameter of 114 mm, a thickness of 50 mm and a length of 610 mm.

The physical properties of the obtained molded products are shown in Table 1.

[0030]

[Table 1]

In Table 1, the molded article according to the present invention is sample No.
Nos. 4 to 8 and Nos. 1 to 3 are shown for comparison.

From Table 1, it can be seen that the molded products of Nos. 4 to 8 to which hematite was added according to the present invention had a remarkably lower thermal conductivity than the molded products of No. 1 to 3 without addition. It is clear that any density has sufficient practical strength.

Example 2 Quicklime (CaO 95%) was dissolved in warm water at 80 ° C.,
The sediment volume of lime milk obtained by dispersing in water with a homomixer was 17 to 20 ml. Silica powder (SiO ₂ 94%) with an average particle size of 6.5 μm was added to the above lime milk with CaO / S.
In addition to the iO ₂ molar ratio of 1.00, a predetermined amount of TiO ₂ powder (rutile, average particle size 1.2 μm) and water were added to make the total amount of water 15 times the solid content. And mixed as above to obtain a raw material slurry. This was stirred at a saturated steam pressure of 12 kg / cm ² and a temperature of 191 ° C. in an autoclave at a rotation speed of 40 rpm while rotating a stirring blade to carry out a hydrothermal synthesis reaction for 5 hours to obtain a slurry of calcium silicate crystals.

The crystal slurry obtained above was heated at 100 ° C. for 24 hours.
After drying for an hour and X-ray diffraction analysis, peaks of rutile crystals were found for those to which xonotlite crystals and TiO ₂ powder were added.

Observation of these crystal slurries with an optical microscope and a scanning electron microscope revealed that in all slurries, zonotolite crystals were three-dimensionally entangled to form a spherical shell having an outer diameter of 5 to 150 μm. Secondary particles were observed. In addition, for those added with TiO ₂ powder,
It was confirmed that the rutile crystal was wrapped in the secondary particles of the xonotlite crystal and physically integrated.

Next, 90 parts (solid content) of the crystal slurry obtained above was mixed with 7 parts of glass fiber and 3 parts of Portland cement.
Parts were added, followed by press dehydration molding and drying at 100 ° C. for 24 hours to obtain a molded body having the same shape as in Example 1. The physical properties of the obtained molded products are shown in Table 2.

[0037]

[Table 2]

In Table 2, the molded article according to the present invention is sample No.
10 to 12, and sample No. 9 is shown for comparison.

It can be seen from Table 2 that the molded products of Nos. 10 to 12 to which rutile was added according to the present invention had a remarkably lower thermal conductivity than the molded product of No. 9 containing no rutile. It is clear that it has practical strength.

Example 3 The same procedure as in Example ₂ was carried out except that the inert substance shown in Table 3 was added in place of the TiO ₂ powder so that the content in the compact was 15%. A molded product having the same shape as in Example 1 was obtained.

The physical properties of the obtained molded product are shown in Table 3.

[0042]

[Table 3]

From Table 3, the molded articles of Nos. 13 to 16 to which the inactive substance was added according to the present invention, were added No. 2 in Table 2.
It is apparent that the thermal conductivity is remarkably reduced as compared with the molded product of No. 9 and has sufficient practical strength.

Claims (2)

[Claims] 1. Secondary particles of calcium silicate crystals, and carbon black, Fe ₃ O ₄ , ZrO ₂ , which is physically integrated with the secondary particles in a state of being enclosed in the secondary particles.
Calcium silicate containing an inorganic inactive substance which is at least one of TiO ₂ , Fe ₂ O ₃ and B ₄ C, and the content of the inactive substance is 10% by weight or more and less than 21% by weight in the molded body. Molded body. 2. A raw material slurry containing a silicic acid raw material, a lime raw material and water is hydrothermally synthesized while heating and stirring under pressure to prepare an aqueous slurry of calcium silicate crystal secondary particles, which is then molded and dried. In the method for producing a calcium silicate compact by using carbon black, Fe ₃ O
_An inorganic inactive substance which is at least one of ₄ , ZrO ₂ , TiO ₂ , Fe ₂ O ₃ and B ₄ C is added to the raw material slurry in an amount of 10% by weight or more and less than 21% by weight in the molded body. And a method for producing a calcium silicate compact.